The arctic environment such as in the Alaskan North Slope oil production area has presented many challenges to pipeline engineers. One of the most difficult challenges has been the protection and preservation of the permafrost surface of the ground over which a pipeline must travel. Fluid temperatures of upwards of 190.degree. F. flowing within the pipeline presents significant difficulty in designing and constructing pipeline supports which will not damage the permafrost or result in pipeline damage if such permafrost melting should occur.
The most common means for supporting an arctic pipeline has been to elevate the pipeline above the permafrost layer. The pipeline is supported in this manner by a number of spaced support members of varying design. In each of these support members, a clamp encircles the pipeline, the clamp being connected to the ground by a structure which will support the weight of the pipeline. At spaced points along the pipeline, the pipeline is tightly clamped and held firmly by an anchoring structure. Intermediate to these anchoring points, supporting saddle clamps and supports of less rigorous construction allow for sliding of the pipeline due to expansion and contraction resulting from differential heating. In all of such support structures, whether anchoring points or intermediate supports, heat transference from the pipeline to the support structure and ultimately the permafrost layer presents a problem.
The high ice (water) content of the permafrost layer can be easily melted by a structure which conducts heat away from the pipeline. Such melting results in sinking and/or heaving of the support structure which can rupture the pipeline with its consequent damage to the environment.
A further problem with such support structures resulting from the fact that the clamps and structures conduct heat from the pipeline are that they act as a heat sink. These so-called "cold spots" present a significant problem to the transportation of crude oil. Cooling can increase the viscosity of the flowing fluids thereby decreasing pipeline efficiency. Further, low melting paraffins can "freeze out" at these cold spots causing a restriction in the pipeline and thus, decreased flow. To date, the only effective means for overcoming the problems of cold spots is to heat the fluid to an even higher temperature with the resultant increased energy costs and an increased possibility of permafrost melting.